// Copyright 2016 The Draco Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#ifndef DRACO_COMPRESSION_ATTRIBUTES_SEQUENTIAL_ATTRIBUTE_ENCODER_H_
#define DRACO_COMPRESSION_ATTRIBUTES_SEQUENTIAL_ATTRIBUTE_ENCODER_H_

#include "draco/compression/attributes/prediction_schemes/prediction_scheme_interface.h"
#include "draco/compression/point_cloud/point_cloud_encoder.h"

namespace draco {

// A base class for encoding attribute values of a single attribute using a
// given sequence of point ids. The default implementation encodes all attribute
// values directly to the buffer but derived classes can perform any custom
// encoding (such as quantization) by overriding the EncodeValues() method.
class SequentialAttributeEncoder {
  public:
    SequentialAttributeEncoder();
    virtual ~SequentialAttributeEncoder() = default;

    // Method that can be used for custom initialization of an attribute encoder,
    // such as creation of prediction schemes and initialization of attribute
    // encoder dependencies.
    // |encoder| is the parent PointCloudEncoder,
    // |attribute_id| is the id of the attribute that is being encoded by this
    // encoder.
    // This method is automatically called by the PointCloudEncoder after all
    // attribute encoders are created and it should not be called explicitly from
    // other places.
    virtual bool Initialize(PointCloudEncoder *encoder, int attribute_id);

    // Initialization for a specific attribute. This can be used mostly for
    // standalone encoding of an attribute without an PointCloudEncoder.
    virtual bool InitializeStandalone(PointAttribute *attribute);

    // Transforms attribute data into format that is going to be encoded
    // losslessly. The transform itself can be lossy.
    virtual bool TransformAttributeToPortableFormat(
        const std::vector<PointIndex> &point_ids);

    // Performs lossless encoding of the transformed attribute data.
    virtual bool EncodePortableAttribute(const std::vector<PointIndex> &point_ids,
                                         EncoderBuffer *out_buffer);

    // Encodes any data related to the portable attribute transform.
    virtual bool EncodeDataNeededByPortableTransform(EncoderBuffer *out_buffer);

    virtual bool IsLossyEncoder() const {
        return false;
    }

    int NumParentAttributes() const {
        return parent_attributes_.size();
    }
    int GetParentAttributeId(int i) const {
        return parent_attributes_[i];
    }

    const PointAttribute *GetPortableAttribute() const {
        if (portable_attribute_ != nullptr)
            return portable_attribute_.get();
        return attribute();
    }

    // Called when this attribute encoder becomes a parent encoder of another
    // encoder.
    void MarkParentAttribute();

    virtual uint8_t GetUniqueId() const {
        return SEQUENTIAL_ATTRIBUTE_ENCODER_GENERIC;
    }

    const PointAttribute *attribute() const {
        return attribute_;
    }
    int attribute_id() const {
        return attribute_id_;
    }
    PointCloudEncoder *encoder() const {
        return encoder_;
    }

  protected:
    // Should be used to initialize newly created prediction scheme.
    // Returns false when the initialization failed (in which case the scheme
    // cannot be used).
    virtual bool InitPredictionScheme(PredictionSchemeInterface *ps);

    // Sets parent attributes for a given prediction scheme. Must be called
    // after all prediction schemes are initialized, but before the prediction
    // scheme is used.
    virtual bool SetPredictionSchemeParentAttributes(
        PredictionSchemeInterface *ps);

    // Encodes all attribute values in the specified order. Should be overridden
    // for specialized  encoders.
    virtual bool EncodeValues(const std::vector<PointIndex> &point_ids,
                              EncoderBuffer *out_buffer);

    bool is_parent_encoder() const {
        return is_parent_encoder_;
    }

    void SetPortableAttribute(std::unique_ptr<PointAttribute> att) {
        portable_attribute_ = std::move(att);
    }

    // Returns a mutable attribute that should be filled by derived encoders with
    // the transformed version of the attribute data. To get a public const
    // version, use the GetPortableAttribute() method.
    PointAttribute *portable_attribute() {
        return portable_attribute_.get();
    }

  private:
    PointCloudEncoder *encoder_;
    const PointAttribute *attribute_;
    int attribute_id_;

    // List of attribute encoders that need to be encoded before this attribute.
    // E.g. The parent attributes may be used to predict values used by this
    // attribute encoder.
    std::vector<int32_t> parent_attributes_;

    bool is_parent_encoder_;

    // Attribute that stores transformed data from the source attribute after it
    // is processed through the ApplyTransform() method. Attribute data stored
    // within this attribute is guaranteed to be encoded losslessly and it can be
    // safely used for prediction of other attributes.
    std::unique_ptr<PointAttribute> portable_attribute_;
};

}  // namespace draco

#endif  // DRACO_COMPRESSION_ATTRIBUTES_SEQUENTIAL_ATTRIBUTE_ENCODER_H_
